How to fix AirPlay audio when you hear nothing at all.

1. Obviously, make sure the volume is turned up and not muted. 

        Places to check the volume:

            -Volume control on the video window (example: youtube videos have a volume control near the lower-left when you mouse over them).

            -Volume control on your device (F12 key on MacBook Airs).

            -Volume control on the projector.

                -If ceiling mounted, use the projector's remote. If the projector has external speakers plugged into it, also check that the speakers are turned on and adjust the volume on them.

                -If wall mounted, use volume switch on the Extron wall switch.

2. Reboot the Apple TV.

        -Option 1

            -Call the tech support person in charge of your building and ask them to remotely restart your AppleTV. 90% of the time they can restart it remotely.

        -Option 2

            -Using an older Apple TV remote (white or all silver) hold down the menu and minus (down arrow) buttons until the light on the Apple TV flashes                 rapidly.

        -Option 3

            -Cycle the power to the Apple TV by unplugging its power cord for a few seconds and then plug it back in.

            You may want to ask tech support or building services to do this for you if your Apple TV requires a ladder or step stool to reach.

            The Apple TV is a small black box.

                -If the projector is ceiling mounted, the Apple TV will likely be sitting on top of the projector.

                -If the projector is wall mounted, the Apple TV will likely be hanging from a ceiling tile.

                    (If the projector is wall mounted, tech support might also need to cycle power to the Extron PoleVault switch box)